Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$216.67	8.715%	$235.5528	$235.55	$235.55	$235.60
Purchase #2	$132.81	9.187%	$145.0113	$145.01	$145.00	$145.00
Purchase #3	$22.78	6.794%	$24.3277	$24.33	$24.35	$24.30
Purchase #4	$185.27	3.251%	$191.2931	$191.29	$191.30	$191.30
Purchase #5	$177.42	4.686%	$185.7339	$185.73	$185.75	$185.70
Purchase #6	$150.78	6.263%	$160.2234	$160.22	$160.20	$160.20
Purchase #7	$72.49	3.127%	$74.7568	$74.76	$74.75	$74.80
7 purchase totals =	$958.22		$1,016.8990	$1,016.89	$1,016.90	$1,016.90